Fig. 2. Hematological analysis and gross anatomy of adult mot. (A) Wild-type red blood cells are terminally differentiated with elliptical morphology, condensed nuclei and hemoglobin-filled cytoplasm. Blood cells collected from adult mot fish exhibit a maturation arrest at the late basophilic erythroblast stage and striking membrane abnormalities. (B) Wright-Giemsa staining of a tissue preparation of the wild-type and mutant fish kidneys reveals an erythroid hyperproliferation in the mot fish with a drastically decreased myeloid/erythroid ratio. A few cells at the early proerythroblast stage also show membrane spiculation. (C) Peripheral blood cells from wild-type zebrafish are compared with concentrated peripheral blood cells from adult cha fish, which show abnormal morphology and differentiation arrest. (D) Gross anatomy of mot fish shows a dilated cardiac chamber compared with wild type. An icteric liver, greatly enlarged kidney and splenomegaly are always present in the adult mot fish. (E) Mean cell volume of red blood cells of wild-type and mutant fish, as measured by an automated Coulter Gen S instrument, shows that wild-type cells have a uniformly distributed volume, whereas mot cells show a significant variation in size. The anisocytosis in mot cells is due to random membrane fragmentation of mot cells.